Reclosable bags, such as those employing rib-and-groove type closures, have been known for decades and have become ubiquitous in food packaging. Such zipper-type closures are known to perform reasonably well for sealing bags between uses, and are readily extruded and weldable to various bag film materials.
For many applications, it is desirable prolonged exposure of the bag contents to air be avoided, such as to maintain freshness. Such applications include, for example, food storage bags and bags for marketing such food products as coffee, shredded cheese, fruit and lunchmeat, and also bags for storing fertilizers and seeds, sensitive electronic components, and materials that react with air. In such applications, most of the air within the bag may be expelled by collapsing the bag about its contents prior to closing the sealing closure.